Scrollbars not reacting to mouse in Canary

A few days ago I noticed I cannot use the scrollbar on several websites. Being the Canary version I'm fine with bugs and regressions like that. At first it looked like it was fixed a few days ago, but it seems it only became less common. For example, it was impossible to use the scrollbar on youtube a few days ago, but now it works fine there - but today, trying to scroll DSOGaming doesn't work. The scrollbar reacts to mouse cursor hover, it changes state after clicking it, but it refuses to move. Sometimes clicking the bar a few times makes it work but it happens rarely. So far this issue occurs on three different machines running Canary and up-to-date Windows 10 Professional. I ran the browser without any extensions enabled, too, so I guess those can be ruled out as a possible cause.